EP2597308A1 - Switchable pressure relief a lubricating device with piston pump - Google Patents

Abstract

The present invention relates to a switchable eccentric drive (18) of a lubricating device (1) with a lubricant reservoir tank (6) and a lubricant pump (2) driven by a drive motor (4), the lubrication device (1) conveying lubricant via at least one delivery line (7) , The lubricant pump (2) has an eccentric shaft (20) and the eccentric shaft (20) has an eccentric section (24, 24 ') arranged eccentrically to a rotation axis (22) of the eccentric shaft (20). The eccentric drive (18) can be operated differently depending on the direction of rotation. Along the eccentric shaft (20) a first eccentric portion (24) and a second eccentric portion (24 ') are arranged, wherein the two eccentric portions (24, 24') are mutually active.

Description

The present invention relates to a switchable pressure relief of a lubricating device according to the preamble of claim 1.

Eccentric drives for radial piston pumps or other assemblies in which a piston is to be placed in an oscillating motion, have long been known. They are simple, inexpensive to produce and extremely reliable. The DE 10 2005 048 567 B3 shows a switchable eccentric drive a lubricating device, in which an eccentric shaft has an eccentric to an axis of rotation of the eccentric shaft arranged eccentric portion on which an eccentric sleeve is rotatably mounted. The rotating eccentric sleeve moves a piston of the lubrication device. By reversing the direction of rotation of Eccentric shaft is a promotion of lubricants by the lubrication on or off.

In lubricating devices, which may be designed as single-line or two-line system, the lubricant is conveyed depending on demand with the aid of a piston pump in a delivery line. From the delivery line, the lubricant passes through distributors to the actual lubrication points. By relieving the pressure in the delivery line, the lubricant is redistributed in the distributor (inlet distributor) or a piston in a second delivery line is moved by the pressure deflected during the discharge (dual-line distributor). In such lubrication after the delivery phase, the pressure relief phase is to be initiated, in which under pressure, excess lubricant is returned to a lubricant reservoir tank, so that the in-line Schiermittel is not too long under pressure, as this can be changed in its consistency , The pressure relief can be done for example via electrically controlled directional control valves. This is associated with high costs for the valves, especially when using fluid grease or grease as a lubricant.

Alternatively to the electrical control of the directional control valves shows WO 2006/108478 A1 a lubrication device in which an axial piston pump has an additional control disk on a drive shaft via which a directional control valve for relieving a delivery line is actuated by means of a rocker mechanism. Thus, the pressure relief can be controlled by changing the direction of rotation of the motor. This control with a control disk and a rocker mechanism is relatively complicated and complex.

The DE 691 10 991 T2 moreover shows a switchable pressure relief device of a lubricating device with a lubricant reservoir tank and a lubricant pump driven by a drive motor, the lubrication device conveying lubricant via a delivery line and the lubricant pump being driven by a drive shaft. The drive shaft is formed as an eccentric shaft with an eccentric to an axis of rotation of the eccentric shaft arranged eccentric portion, wherein the eccentric portion forms a rotational direction-dependent eccentric and the eccentric actuates a pressure relief device.

By the DE 10 2007 045 644 A1 a lubricant driven by a drive motor lubricant pump is known, which has a lubricating device with a lubricant reservoir tank. The lubrication device delivers via a conveyor line lubricant, wherein the lubricant pump is driven by a drive shaft. The drive shaft is designed as an eccentric shaft with two eccentric to an axis of rotation of the eccentric shaft arranged eccentric sections, wherein an eccentric sleeve is rotatably mounted on each eccentric. At least one eccentric section forms a direction of rotation-dependent eccentric drive.

The object of the invention is to turn on and off with simple means via a mechanical control a promotion of lubricants through the lubrication and at the same time initiate a pressure relief in the delivery line when you turn off.

To solve the problem, it is proposed that the from the DE 10 2005 048 567 B3 known eccentric shaft is supplemented by a second eccentric section. The first The eccentric section serves to drive the pump piston, while the second eccentric section subsequently actuates the directional control valves for pressure relief. It is inventively provided that the two eccentric sections are active in opposite directions of rotation of the eccentric shaft. By 'active' is meant that the stroke of an eccentric section is greater than zero.

The eccentric drive according to the invention has two identical switchable eccentric sections, which can be used for different functions. Depending on the direction of rotation of the eccentric shaft, one of the two eccentric drives is always active. Thus, either the promotion of lubricant or the pressure relief of the delivery line can be controlled by the reversal of the direction of rotation in control of the simplest way.

The eccentric shaft and the eccentric sections arranged on the eccentric shaft are simple and durable components, such as e.g. Cylinders, bores or discs made of metal, which can be produced easily and inexpensively. The eccentric section e.g. may include a cylindrically shaped bolt which is arranged eccentrically on the eccentric shaft.

In a preferred embodiment it is provided that an eccentric sleeve is rotatably mounted on the respective eccentric, wherein the eccentric sleeve eccentric by rotation about the eccentric by an angle of less than or equal to 180 ° to a first stop in a first position relative to the axis of rotation of the eccentric shaft is arranged, and by turning back the eccentric shaft to a second stop the eccentric sleeve in a second position relative to the axis of rotation of the Eccentric shaft is arranged concentrically. Thus, it is possible, for example, to realize a drive of an oscillating pump piston by the eccentrically rotating eccentric sleeve of the first eccentric section, wherein after switching to the second position of the pump piston on the concentrically rotating eccentric sleeve rotates only motionless and performs no oscillating motion more. The function is comparable to that of a freewheel. The switching thus causes a switching on and off of the corresponding function of the lubrication device.

For the invention, it is particularly advantageous that the first eccentric with the corresponding eccentric sleeve of the promotion of lubricant through the feed line is used and the second eccentric with the corresponding eccentric a pressure relief of the delivery line is used. Since the two eccentric sections are mutually active in the preferred embodiment, the pressure relief during the delivery phase is switched off; If the delivery phase is ended by reversing the direction of rotation of the eccentric shaft of the switchable eccentric drive, the pressure relief is active. The pressure relief can, for example, be realized in such a way that a piston oscillating through the eccentric sleeve switches a pressure relief device, for example a relief valve, opens and closes several times.

In one embodiment of the invention, it is possible that the lubrication device has more than one delivery line and each delivery line is associated with a respective first and second eccentric with the corresponding eccentric sleeve, all eccentric are arranged on the same eccentric shaft of the switchable eccentric. The lubrication device can eg. be realized in such a way that an eccentric sleeve drives two drive elements, so that the first eccentric sleeve of the promotion of lubricant is used by a first delivery line and at the same time serves to relieve the pressure of the second delivery line. The second eccentric sleeve serves to convey lubricant through the second delivery line and at the same time serves to depressurize the first delivery line. Thus, for example, a two-line system can be realized in which pressure is built up and relieved alternately in the lines.

All lubrication points to be operated by the lubrication device can be simultaneously lubricated by the arrangement on the common eccentric shaft and switched off at the same time, the pressure reliefs for the corresponding delivery lines being active after the shutdown.

Figur 1

eine schematische Darstellung einer Schmiereinrichtung aus dem Stand der Technik;

Figur 2

einen Längsschnitt durch ein Pumpengehäuse mit einem erfindungsgemäßen schaltbaren Exzenterantrieb im Innern;

Figur 3

ein Schnitt A : A aus Figur 2; und

Figur 4

ein Schnitt B : B aus Figur 2.

Further features and advantages of the present invention will be explained in more detail with reference to FIGS. The specified features may also be the subject of the invention individually and in any combinations which deviate from the described and illustrated combination. Show it:

FIG. 1

a schematic representation of a lubrication device of the prior art;

FIG. 2

a longitudinal section through a pump housing with a switchable eccentric drive according to the invention in the interior;

FIG. 3

a section A: A out FIG. 2 ; and

FIG. 4

a section B: B off FIG. 2 ,

FIG. 1 shows a lubricating device 1 with a lubricant pump 2 (for example, a radial piston pump), the pump elements 3 are actuated by an electric drive motor 4 via, for example, an oscillating drive piston 5 to promote lubricant from a lubricant reservoir tank 6 in a delivery line 7. For this purpose, the drive motor 4 has, for example, a switchable eccentric drive (in FIG FIG. 1 not visible), which indirectly moves the drive piston 5. The lubricant reservoir tank 6 may additionally have a stirring device 8. The delivery line 7 leads in the illustrated, exemplary case to two distributors 9, from which corresponding supply lines 10 branch off to the individual lubrication points.

In the delivery line 7, a pressure switch 11 is provided, which ends the lubricant delivery by emitting a corresponding signal of a controller 12 to the drive motor 4 upon reaching a maximum pump pressure provided. The pressure switch 11 could also be replaced by a timer. To convey lubricant, a plurality of delivery lines 7, which can also be supplied by different pump elements 3, can be provided.

In a housing 15 of the lubricant pump 2, a pressure relief unit 13 is disposed in the interior for pressure relief of the delivery line 7 after a delivery phase of lubricant. At the pressure relief unit 13, a return line 14 is connected for lubricant. The pressure relief unit 13 closes the return flow line 14 in the delivery phase, in which the lubrication points are to be supplied with lubricant. In the subsequent pressure relief phase, the reflux line 14 is opened by the pressure relief unit 13 and the excess lubricant can via the return line 14 escape This reduces the pressure in the delivery line.

In FIG. 2 is a longitudinal section through the housing 15 of the lubricant pump 2 according to the invention shown in detail. The lubricant pump 2 has a switchable eccentric drive 18 according to the invention. The FIGS. 3 and 4 show two sections through the switchable eccentric drive 18th

In the housing 15, an eccentric shaft 20 is rotatably mounted. An axis of rotation of the eccentric shaft 20 is provided with the reference numeral 22. The eccentric shaft 20 has two eccentric sections 24 and 24 ', which are arranged separately from one another and are of identical construction in general, which are designed, for example, in each case as a bolt. The eccentric sections 24 and 24 'define on the eccentric shaft 20 two different functional planes 26 and 26'. The eccentricity of the eccentric portions 24 and 24 'with respect to the axis of rotation 22 is denoted by e1. At the eccentric portions 24 and 24 'of the eccentric shaft 20 each have an identically shaped eccentric sleeve 28 and 28' rotatably mounted, wherein an orientation of the respective eccentric sleeves 28 and 28 'on the eccentric shaft 20 is correspondingly different. Further information will follow later. The two eccentric sleeves 28 and 28 'may also have different dimensions as the eccentricities e1.

The eccentric sleeves 28 and 28 'have a circular outer contour, as shown in FIGS FIGS. 3 and 4 is apparent. Eccentrically to a central axis 30 of the eccentric sleeve 28 (functional level 26) has a bore 32 in the eccentric sleeve 28 is present. The bore 32 has the same diameter as the eccentric portion 24 of the eccentric shaft 20 and serves as a bearing of the eccentric sleeve 28 on the eccentric portion 24. The eccentricity of the bore 32 with respect to the central axis 22 of the eccentric sleeve 28 is denoted by e2. In the position shown in function level 26, the eccentricity e1 of the eccentric portion 24 and the eccentricity e2 of the eccentric sleeve 28 add up. FIG. 3 shows a section through the functional level 26 for better clarity.

In the functional plane 26 ', the eccentric sleeve 28' is rotated about the eccentric portion 24 ', in such a way that the axis of rotation 22 and a central axis 30' of the eccentric sleeve 28 'are superimposed. There is thus no eccentricity, because the eccentricities e1 and e2 cancel each other out. The eccentric sleeve 28 'is arranged concentrically on the eccentric shaft 20. FIG. 4 shows for better clarity a section through the functional plane 26 '.

On the eccentric shaft 20 is in the functional plane 26 and 26 'each have a pin 34 and 34' is provided, each of which engages in a circular arc-shaped groove 36 and 36 'of the eccentric sleeve 28 and 28'. The groove 36 or 36 'extends concentrically to the bore 32 or 32' in the eccentric sleeve 28 or 28 'and encloses an angle of about 180 °. The grooves 36 and 36 'and the pins 34 and 34' have the function of a rotation angle limit and a stop and ensure that on the one hand the eccentric sleeve 28 and 28 'only by a certain angle relative to the eccentric 24 and 24' is rotatable. On the other hand, with the help of the pins 34 and 34 'and the groove 36 and 36', a torque from the eccentric shaft 20 to the respective eccentric sleeves 28 and 28 'are transmitted to a rotation of the eccentric shaft 20 together with the eccentric sleeves 28 and 28' to enable.

As soon as the end of the groove 36 or 36 'comes into contact with the pin 34 or 34', the relative movement between the eccentric shaft 20 and the eccentric sleeve 28 is terminated and it is the torque of the eccentric shaft 20 on the eccentric sleeves 28 and 28 ' transfer.

For conveying lubricant into the corresponding supply lines 10 to the individual lubrication points, the functional level 26 is provided. FIG. 3 shows the corresponding situation. For this purpose, the drive piston 5 of the lubricant pump 2 is located on the outer diameter of the eccentric eccentric shaft 20 positioned on the eccentric sleeve 28 and is held, for example, by a spring, not shown, in abutment with the eccentric sleeve 28. By turning the eccentric shaft 20, for example, counterclockwise (see reference numeral 40 in FIG FIG. 3 ) is transmitted via the pin 34, the torque from the eccentric shaft 20 on the eccentric sleeve 28, whereby the drive piston 5 in an oscillating movement (see reference numeral 38 in FIG. 3 ). A stroke H of the drive piston 5 is calculated from H = 2 * (e1 + e2).

At the in FIG. 2 illustrated embodiment, the eccentricity e1 of the eccentric portion 24 and 24 'is the same size as the eccentricity e2 of the eccentric sleeve 28 and 28'. However, this does not always have to be this way.

The function level 26 'is provided for pressure relief of the delivery line 7. For this purpose, the pin 34 'beats relative to the arrangement of the pin 34 of the functional plane 26 at the opposite end of the groove 36'. That means that in the in FIGS. 3 and 4 shown position, the pin 34 strikes the pin 34 'at the opposite end of the respective groove. FIG. 4 shows the corresponding situation in the functional level 26 '. The eccentric sleeve 28 'is arranged by the described arrangement in the functional plane 26' concentric with the axis of rotation 22 of the eccentric shaft 20. In the functional level 26 'is an actuator 42 for the pressure relief unit 13 on the eccentric sleeve 28' resiliently. In the in FIG. 4 shown position is not moved by the position of the eccentric sleeve 28 ', the actuator 42, since the eccentricity e1 of the eccentric 24' and the eccentricity e2 of the eccentric sleeve 28 'subtract in this position. Thus, the stroke H of the actuating element 42 is H = 2 * (e1-e2) = 0, which is desired in the conveying phase of the functional plane 26. The function is comparable to that of a freewheel.

Now, if the direction of rotation of the eccentric shaft 20 of the mechanically switchable eccentric drive 18 is reversed, the pins 34 and 34 'each travel to the opposite end of the groove 36 and 36'. As a result, the eccentric sleeve 28 and 28 'rotates by approximately 180 ° relative to the eccentric shaft 20. This means that now in function level 26 no stroke for oscillating the drive piston 5 is generated because no eccentricity at the contact surface between the eccentric sleeve 28 and the drive piston 5 occurs. The eccentric sleeve 28 is now in free-running. As a result, the drive piston 5, despite a rotation of the eccentric shaft 20 performs no oscillating movement. The promotion of lubricant is turned off.

At the same time, the eccentric sleeve 28 'is arranged eccentrically on the eccentric shaft 20 in the functional plane 26', so that an oscillating movement of the actuating element 42 of the pressure relief unit 13 is generated. The actuator 42 opens to the For example, a temporarily arranged in the delivery line 7 relief valve, wherein under pressure, excess lubricant in the delivery line 7 the lubricant supply tank 6 is returned via the return flow line 14 again. The pressure relief is active. By the eccentric drive 18 according to the invention, the pressure relief is always turned on when the delivery operation of the lubricant pump 2 is turned off. Conversely, if the delivery mode is switched on, the pressure relief is switched off.

The relief valve of the pressure relief unit 13 could be actuated via the actuator 42 directly or via an additional pin which switches the relief valve. It is also possible that the actuating element 42 opens the return flow line 14 directly or via an additional piston in the function of a directional control valve. Furthermore, it is possible that the relief valve is similar to a normal pump element, but without a check valve is formed. The closure is then performed by the actuator 42, which actuates a metering piston of the pump element.

In an embodiment, not shown, it is possible that each functional level 26, 26 'is equipped both with a drive piston 5 for conveying lubricant and with an actuating element 42 for the pressure relief unit 13. This means that the lubrication device has two delivery lines 7 for conveying lubricant and thus represents a two-line system. In this case, for example, applies to a first conveyor line 7, that the function level 26 promotes Schmittmittel, the functional level 26 'realized the pressure relief. For a second delivery line 7 applies then that the function plane 26 'promotes Schmittmittel, the functional level 26 realizes the pressure relief. This ensures the function of the two-line system, in which pressure is built up and relieved alternately in the lines.

In a further embodiment, not shown, it is possible that the eccentric shaft 20 of the switchable eccentric drive 18 has more than two functional levels. The two functional levels 26 and 26 'could be duplicated, for example, so that a two-line system is created. Here, too, the function of the two-line system is ensured, in which pressure is built up and relieved alternately in the lines. Each delivery line can convey lubricant via the process described above and relieve pressure when the delivery is switched off.

Claims (7)

Switchable pressure relief device (18) of a lubricating device (1) with a lubricant reservoir tank (6) and a lubricant pump (2) drivable by a drive motor (4), the lubrication device (1) conveying lubricant via at least one delivery line (7), the lubricant pump ( 2) is driven by a drive shaft, wherein the drive shaft as eccentric shaft (20) with an eccentric to a rotational axis (22) of the eccentric shaft (20) arranged eccentric portion (24, 24 ') is formed, and that the eccentric shaft (20) a pressure relief device (13) actuated, characterized in that the eccentric shaft (20) has at least two eccentric portions (24, 24 '), wherein at each eccentric portion (24, 24') an eccentric sleeve (28, 28 ') is rotatably mounted, and the eccentric sleeve (28, 28 ') with the respective eccentric portion (24, 24') form the direction of rotation-dependent eccentric drive (18). Eccentric drive (18) according to claim 1, characterized in that along the eccentric shaft (20) a first and a second eccentric portion (24, 24 ') and a first and a second eccentric sleeve (28, 28') are arranged, the first and form a second eccentric drive (18), and that the first and the second eccentric drive (18) are active in different directions of rotation of the eccentric shaft. Eccentric drive (18) according to claim 1 or 2, characterized in that on the respective eccentric portion (24, 24 ') an eccentric sleeve (28, 28 ') is rotatably mounted, wherein the eccentric sleeve (28, 28') by a rotation about the eccentric portion (24, 24 ') by an angle of less than or equal to 180 ° to a first stop in a first position relative to the axis of rotation (22 ) of the eccentric shaft (20) is arranged eccentrically, and by turning back the eccentric shaft (20) to a second stop the eccentric sleeve (28, 28 ') in a second position relative to the axis of rotation (22) of the eccentric shaft (20) is arranged concentrically. Eccentric drive (18) according to claim 1, 2 or 3, characterized in that the first eccentric portion (24) with the corresponding eccentric sleeve (28) of the promotion of lubricant through the feed line (7) and the second eccentric portion (24 ') with the corresponding eccentric sleeve (28 ') a pressure relief of the delivery line (7) is used. Eccentric drive (18) according to claim 4, characterized in that when the function of the first eccentric portion (24), the function of the second eccentric portion (24 ') is turned off and with the function of the first eccentric (24) off the function of the second eccentric (24' ) is turned on. Eccentric drive (18) according to claim 5, characterized in that by reversing the direction of rotation (40) of the eccentric shaft (20), the functions of the eccentric portions (24, 24 ') respectively switched on and off. Eccentric drive (18) according to one of the preceding claims, characterized in that the Lubricating device (1) more than one delivery line (7) and each delivery line (7) each have a first and a second eccentric portion (24, 24 ') associated with the corresponding eccentric sleeve (28, 28'), wherein all eccentric sections on the same Eccentric shaft (20) are arranged.

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